An optical device in which polarizers are arranged so that the polarization direction differs in respective small regions and electronic devices formed by integrating the optical device are commercialized as typified by displays and measuring devices. For example, stereo video can be viewed by simple polarized glasses by bonding a filter in which micro-polarizers are arranged regularly to a flat panel display such as a liquid crystal monitor.
Incidentally, a relatively large-sized system dealing with polarization split in a device such as a liquid crystal projector, polarization directions are uniformly controlled in respective light paths as the device has light paths of RGB independently. In this case, the size of the whole system will be relatively large, which is several centimeters square, though it is not necessary to change the polarizer's direction in respective pixel regions.
As heat resistance is required particularly in the liquid crystal projector, a reflection-type wire-grid polarizer is widely used in view of characteristic lifetime of the device. In the reflection-type wire-grid polarizer, the thickness thereof can be suppressed to several 100 nm or less when visible light is polarized. However, extinction is performed by reflection in the reflection-type wire-grid polarizer. Therefore, reflection return light from the polarizer will be stray light or flare according to installation places in the set, which may affect video quality.
Accordingly, an absorption-type wire-grid polarizer (WGP) using an inorganic polarizer is proposed (for example, see JP-A-2008-216956 (Patent Document 1)). The WGP includes a reflection layer made of belt-shaped thin films formed in one dimensional grid shape with a pitch smaller than a wavelength of light in a used bandwidth, a dielectric layer formed on the reflection layer and an absorption layer made of inorganic fine particles formed on the dielectric layer. The inorganic fine particles of the absorption layer have light absorption action.
The above absorption-type WGP can be manufactured by the following method.
First, a device in which the WGP is formed, for example, a photoelectric conversion device 100 is prepared as shown in FIG. 13A. Next, a planarization layer 101 is formed on a surface of the photoelectric conversion device 100 as shown in FIG. 13B. Next, an insulating layer 102 is formed on the planarization layer 101 as shown in FIG. 13C. Then, a reflection layer 103 made of metal thin lines is formed on the insulating layer 102 with lines and spaces. Subsequently, an insulating layer 104 is formed on the reflection layer 103. Next, an absorption layer 105 is formed in a rectangular island pattern with island distribution by using inorganic materials having absorptive action, for example, metal, semiconductor materials and the like.
According to the above method, the absorption-type WGP allowing incident light to be spatially split into polarized light can be integrally formed. The photoelectric conversion device formed by this method can be formed by normal semiconductor processes, which can be applied to small video devices.